Physical Sciences and Mathematics Commons^™

Calcite Depression In Bastnaesite-Calcite Flotation System Using Organic Acids, Emmy Muhoza

Graduate Theses, Dissertations, and Problem Reports

Bastnaesite is the primary source of light REEs, namely cerium (Ce), lanthanum (La), praseodymium (Pr), neodymium (Nd), to name a few. Bastnaesite is typically concentrated using the froth flotation beneficiation method. Flotation of bastnaesite suffers from high reagent consumption due to the similar surface characteristics of bastnaesite and associated gangue minerals, including calcite. Additionally, complex stages of high-temperature conditioning are often required to suppress the detrimental impact of dissolved calcium ions on the flotation of bastnaesite. This research seeks to investigate the capabilities of organic acids in the bastnaesite-calcite flotation systems to selectively depress calcite minerals and effectively chelate calcium …

Investigation Of Complex Formation By Oligomers Of Cytosine And Guanosine, Steven Roberts Davis

Chemistry & Biochemistry Theses & Dissertations

Duplex formation between oligo(C:G) _n where n=3 to 4 was shown not to occur under conditions favorable for duplex formation between poly G and poly C. Instead, a stable guano sine self-structure was found to form which a T_m of 50°C for (Gp)₃ and 80°C for (Gp)₄ at strand concentrations of 10^-5M in 1M NaCl. Neither a duplex nor a self-structure formed in the absence of salt.

Oligomers of guanosine and cytosine were obtained by basic hydrolysis and separated according to chain length using DEAE Sephadex column chromatography. Separation of cytosine oligomers with chain lengths …

The Thermal And Photolytic Rearrangements Of Isatoic Acid Diazide, Ana Alejandre Ciereszko

Chemistry & Biochemistry Theses & Dissertations

The primary objective of this research has been the thermolysis and photolysis of isatoic acid diazide 1. Thermolysis in low boiling solvents produced the acylazido benzimidazolone 10, while refluxing in high boiling solvents gave rise to the imidazoindazoline 31, presumably via Curtius rearrangements.

Photolysis of the diazide in methylene chloride gave rise to two photo products, 10 and 31, while photolysis in tetrahydrofuran produced only 31.

A study of the spectral and chemical characteristics of these products have been carried out.

The Synthesis And Characterization Of The 2,2'-Bisacylazide Of 2,2'-Diphenyldicarboxylic Acid, Subrata Chatterjee

Chemistry & Biochemistry Theses & Dissertations

The primary objective of this investigation w2s the photolytic and thermal characterization of a newly synthesized aromatic diacylazide, the 2,2'-bisacylazide~ of 2,2'-diphenyldicarboxylic acid 19. Photolysis of the azide in acetone ~ave rise to a mixture of photoproducts, one of which is a known system, 6(5-H)-phenanthridionone 28, while photolysis of 19 in ethanol gave ris,2 to the corresponding hydroxamic acid ester 40.

The Bromination Of 1,1,1-Ethanetriacetic Acid, John A. Gurney

Theses and Dissertations

Essential to the entire field of Organic Chemistry is the nature of the carbon to carbon bond. Our current concepts and guiding principles concerning it are almost solely constructed from aliphatic compounds, certain simple ring species, and aromatic systems. Except for special cases, aliphatic and aromatic types are felt to be mildly strained or free from internal tension while the alicylic small and medium ring compounds are the so-called strained molecules. These strained compounds involve bending back or compression of two of the four carbon bonds from an equilibrium position. Distortions of more complex origin occur in the paracyclophanes and …